Peroxyacetylnitrate (PAN) is formed by addition of NO 2 to the corresponding per

Question

Peroxyacetylnitrate (PAN) is formed by addition of NO2 to the corresponding peroxyacetyl radical. PAN is considered to be a NOxreservoir species, able to transport NOx from polluted to remote regions, where it decomposes and releases NO2. PAN is also an irritant, and one of the reasons why your eyes become itchy in summertime smog.

CH3C(=O)O2 + NO2 --> CH3C(=O)O2NO2

PAN dissociates (when heated):

CH3C(=O)O2NO2 --> CH3C(=O)O2 + NO2,

k' = 1.86×1016×e(-13500 Kelvin)/T s-1

Because PAN is stable at cool temperatures, and relatively inert w.r.t. oxidation by OH and photolysis, and can be transported over long distances (e.g., to the North Pole).

a. Calculate the (1/e) lifetime (in days) of PAN as it releases NO2 at -17.9 C.

Thanks

Explanation / Answer

CH3C(=O)O2NO2 --> CH3C(=O)O2 + NO2,

k' = 1.86×1016×e(-13500 Kelvin)/T s-1

T = -17.9 C = 255.1 K

k' = (1.86*10^16)*e^(-13500/255.1)

  k' = 1.93404*10^(-7) s^-1.

Time (t) = 1 / k'    = 1/(1.93404*10^(-7)) = 5170523.88 sec

Time (t) = 5170523.88 *(1/(3600*24)) = 59.84 days

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